| 摘要 |
PURPOSE:To obtain a thin-type optical disk molded substrate having small double refractivity and little warpage by injection compression molding a polycarbonate resin under specified molding conditions into specified thickness or smaller to produce a disk substrate. CONSTITUTION:A polycarbonate resin is subjected to injection compression molding with an injection molding machine under molding conditions of 370-390 deg.C molding temp., 120-140 deg.C die temp., and 20-50 ton pressure to form an optical disk substrate having <=1.0mm thickness. By this method, an optical disk substrate of a thin type having excellent double refractivity and little warpage can be obtd. by using a transparent polycarbonate resin. Thereby, increase in the massproductivity and decrease in the cost is realized. Further, high-density input of picture images is possible and the amt. of record is increased. |
